1. Field of Invention
The invention relates to a developing cartridge, a process unit provided with the developing cartridge, and an image forming apparatus provided with the developing cartridge or the process unit.
2. Description of Related Art
A known image forming apparatus, such as a laser printer, removably sets therein a toner cartridge into which toner is filled. Such laser printer is provided with a detection device that determines whether the toner cartridge is new, for example, to prevent incorrect detection of the usage limitation of the toner cartridge.
For example, Japanese Laid-Open Patent Publication No. 3-279965 proposes a device that automatically detects whether a cartridge mounted on an image forming apparatus is unused. As a drive transmission system of the cartridge is driven at the time of using the cartridge mounted on the image forming apparatus, a driving interlocking member is displaced on the cartridge. A detection device provided on the image forming apparatus detects whether displacement of the driving interlocking member is a specified amount. The specified amount of the driving interlocking member is associated with an initial state of the cartridge. Thus, a determination as to whether the cartridge is new is automatically made.
In the detection device, the driving interlocking member is always displaced as the drive force is applied to the drive force transmission system of the cartridge. When a cartridge is checked or examined alone, without being set in a printer, on its roller operations after assembly at a production line, the drive force is applied to the drive force transmission system of the cartridge. Accordingly, the shipped cartridge is incorrectly detected as a used cartridge, even when the cartridge is new. Thus, such an operation check leads to an improper determination of the cartridge status as to whether the cartridge is new.